The present invention relates to a fastening element for fastening to a wall having an opening therethrough which is accessible only on one side of the wall, comprising a cylindrical upsettable shell having a flanged end and a cylindrical inset member disposed in the shell.
There are already known fastening elements of the above type used at rivet joints, in which the upsettable shell is upset with the aid of a rivet bolt in such a way that it forms a bulge. The two workpieces to be riveted, lying loosely one upon the other, are enclosed between the flange of the upsettable shell and the bulge that has been formed, in fixed position. The rivet bolt, which after the riveting process no longer has any function, is thereupon cut off snugly with the flange surface, so that it now serves only as a filler pin. So that the rivet bolt cannot drop out of the rivet joint, it is often losably jointed with the upsettable shell.
In these known rivet joints, the threaded bolt is not joined with the upsetting shell in such a way, however, that it can absorb the loads raising from the forces required for the riveting process. On the contrary, in the rivet bolt there are provided desired breaking places, with which it is supposed to be assured that the bolt breaks rather than the connection or rather than have the bolt tear or the bulge yield, by any of which the rivet joint would be destroyed. At any rate, the connection between bolt and shell in the known rivet joints is not constructed in such a way that the bolt would be suited to serve as a fastening element for further construction parts.
Further, it is likewise a known practice to sink rivet sockets into a rivet bore and to upset them with the aid of a riveting tool carrying a threaded mandrel. After the upsetting, the mouthpiece of the tool carrying the threaded mandrel is then turned out of the rivet. These known rivet sockets have the disadvantage that the thread is formed in the wall of the cylindrical upsettable sleeve forming the rivet sockets. Since the shell material, in order to be upsettable, cannot be chosen too strong, the socket thread cannot absorb any high loads. These rivet sockets, therefore, are not suited for the fastening of further construction parts in any case having high loads.
Underlying the present invention is the problem of providing a fastening element of the type described above, which is suited for fastening on to the threaded bolts further construction parts, the threaded bolts being able to absorb extremely high stresses in the form of variable tensile and shearing forces, without breaking the connection between the threaded bolt and the upsettable shell.